Counting tube circuits



Sept. 5, 1961 D. GLASER COUNTING TUBE CIRCUITS Filed Feb. 16, 1959 s gmCLEAR AND ZERO SET CLEAR AND ZERO SET INVENTOR. DAV/D GL/LSER C fin PULS E GENERATOR A TTORNE Y Unite rates Patent 2,999,183 COUNTING TUBECIRCUITS David Glaser, Middlesex, N.J., assignor to BurroughsCorporation, Detroit, Mich., a corporation of Michigan Filed Feb. 16,1959, Ser. No. 793,627 Claims. (Cl. 315-8.5)

This invention relates to multiple output electronic counting tubes andto improved circuits for using such tubes.

Electronic counting tubes generally include a plurality of electrodesarranged in groups, and, under the influence of an external drivingmeans, an electron beam switches from group to group during the countingoperation. Under some circumstances, it is desirable to be able to stopsuch a tube at a particular counting position. In the past, this hasbeen accomplished 'by inactivating the external driving means. However,this type of indirect inactivation of the counting tube does notpositively lock or inactivate the counter, since it is possible forstray noise to affect the tube from the portion of the circuitry betweenthe external driving means and the tube itself. Such stray noise maycause undesired, spurious counting.

Accordingly, the principles and objects of the present invention areconcerned with an improved circuit for stopping and locking a countingtube in any desired position during a counting operation, withsubstantially no opportunity for the tube to execute a spurious countingoperation.

In brief, the invention relates to a magnetron-type multi-positionelectron beam tube which operates with crossed electric and magneticfields and includes a central cathode and a plurality of groups ofelectrodes, from each of which an output signal is derived. Each groupof electrodes includes an output target electrode, a spade electrodeadapted to form and hold an electron beam on its associated targetelectrode, and a switching electrode which serves to switch an electronbeam from one group of electrodes to the next. A suitable externaldriving means is provided for operating the switching electrodes andeffecting the counting operation. According to the invention, means areprovided for stopping the tube at any particular count. This meansoperates by biasing the switching electrodes at such a level ofpotential that they cannot affect the electron beam, regardless of theaction of the external driving means. The means of the inventionincludes unidirectional current flow means coupled to all of theswitching electrodes,

this means being capable of operating in two states, one

state in which it does not altect the switching electrodes and the tubecounts in normal fashion, and one state in which it is activated todisable the switching electrodes and thus prevent the tube fromcounting. In the second state, the tube counting operation is stopped ata desired position or count which may be held as long as desired.

The invention is described in greater detail by reference to the drawingwherein:

FIG. 1 is a perspective view of an electron discharge device utilized inpracticing the invention;

HG. 2 is a schematic representation of the device of FIG. 1 and acircuit embodying the invention; and

FIG. 3 is a schematic representation of a modification of the circuit ofFIG. 1.

The circuits and systems described below are particularly suitable foruse with a type 6700 multi-position electron beam tube. This type oftube is shown in FIG. 1 as tube and includes, briefly, an envelope 12which contains a central longitudinally elongated cathode 14 and tengroups of electrodes spaced radially equidistantly from the cathode andsurrounding the cathode. Each group of electrodes includes a generallyU-shaped elon- Patented Sept. 5, 1961 gated spade electrode 16 and agenerally L-shaped target electrode 18 positioned so that each targetoccupies the space between adjacent spade electrodes. Each spadeelectrode serves to form and hold an electron beam on its correspondingtarget electrode. A generally rod-like switching electrode 20 is alsoincluded in each group of electrodes and is positioned between one edgeof each target electrode and the adjacent spade electrode. The switchingelectrodes are known as switching grids. An open-ended cylindricalpermanent magnet 22 is provided surrounding the tube envelope andcoaxial therewith. The magnet provides an axial magnetic field which isutilized in conjunction with electric fields within the tube to form andswitch an electron beam from the cathode to each of the groups ofelectrodes. The direction in which the beam switches, that is clockwiseor counterclockwise, is always the same and is determined by theelectron beam is formed and directed to the corresponding targetelectrode. The electron beam may be switched from one target electrodeto the next by thus suitably altering the electrical potentials of aspade or switching grid. Under normal operating conditions, wheneverelectrode voltages are such that a beam might be sup ported at severalpositions, the beam will switch to the most leading position and lock inat this position.

In the circuit of FIG. 2, the tube 10 is shown in schematic, linear formwith the positions or groups of electrodes thereof numbered seriallyfrom 0 to 9. In the circuit, the cathode 14 is connected through asuitable resistor 24 to ground. Each of the spade electrodes 16 iscoupled through a spade load resistor 26 to a spade buss 28. The spadebuss 28 is coupled through a common spade resistor 30 to a suitablepositive DC. power supply V A suitable clear and zero-set circuit 32 forclearing an electron beam in the tube and resetting it at the 0 positionis coupled to the spade buss and the spade electrode at the 0 position.A typical zero-set circuit operates by first reducing the potential ofthe spade buss 23 to a level at which a beam cannot be maintained at anyposition and then holding the 0 spade at a lower voltage level than theother spades until a beam forms at the 0 position.

The output or target electrodes 18 are each coupled through a suitableload resistor 34 to a target buss 36 which is connected to a suitablepositive DC power supply V Each target electrode is also connected to asuitable utilization circuit which may be, for example, a type 6844Aindicator tube or the like. In FIG. 2, each of the targets is shownconnected to an element 38 which represents one of the numeral glowcathodes 38 of such an indicator tube. For purposes of simplifying thedrawing, only the indicator glow cathodes of the indicator tube areshown.

The switching grid electrodes 20 may be connected in several differentways. In one arrangement, shown in FIG. 2, the grids at theeven-numbered positions are connected in one set to a common buss 40 andthe grids at the odd-numbered positions are connected in another set toa common buss 42. The buss 40 is connected to the output of a cathodefollower 44, and the buss 42 is connected to the output of a cathodefollower 46. The input of each cathode follower is connected to one ofthe outputs of a flip-flop circuit 48. As first one and then the otheroutput of the flip-flop operates, pulses applied through the cathodefollowers to the grid busses 3 40 and 42 cause an electron beam in thetube to move from position to position.

According to the invention, means are provided for stopping the countingoperation of the tube 10 and locking the electron beam at any desiredposition, This is accomplished by rendering the switching grids 20inoperative at the desired instant by biasing them all at such a highpositive level of potential that they cannot afiect the electron beam,regardless of the action of the flip-flop circuit &3. In the embodimentof the invention shown in FIG. 2, this means comprises two diodes t and52 connected between the busses, the cathodes of the diodes beingconnected to the busses 40 and 42 and their anodes being connectedtogether. The anodes of the diodes are also connected through a lead 54to a two-terminal switch 55 having one terminal 56 coupled to a sourceof reference potential such as ground and a second terminal 53 coupledto a source of positive voltage V The reference potential such as groundserves to reverseeias the diodes and render them inoperative when thetube is performing a normal counting operation. The positive voltage Vserves to render the diodes conductive, whereby the busses 40 and 42 andthe switching grids 29 are raised to the positive potential V at whichthe normal switching function of the tube is interrupted.

Thus, in operation of the circuit of FIG. 2, when it is desired to allowthe tube to count in normal fashion, the switch 55 is operated so thatthe lead 54 is connected to the terminal 56 and to ground and the diodes5t; and 52 are thereby rendered non-conductive and they do not aifectthe operation of the switching electrodes. When, during the normalcounting operation, it is desired to stop the count and to lock anelectron beam in a desired position in the tube 13, the switch 55 isoperated so that the lead 54 is in contact with the terminal 53 and thepositive voltage V and the diodes 50 and 52 are thus renderedconductive. When the diodes conduct current, the busses 4t) and 42 andthe switching grids are raised to the positive potential V at which theswitching grids are unable to perform a switching function even ifswitching pulses are applied thereto from the flip-flop circuit 48.

In a typical operative circuit, the target supply voltage V may be about300 volts; the spade supply voltage V may be about 200 volts; and thediode positive bias voltage V is about 200 volts.

In a modified circuit for operating a beam switching tube shown in FIG.3, the tube 10 is used and all of the circuit connections may beidentical except that the switching electrodes 2% are all connectedtogether to a single buss 6t and to a suitable source 62 of negativeswitching pulses. Such pulses are of controlled time duration to providethe desired one-step switching of an electron beam in the tube 10. Inthis embodiment of the invention, the count-stopping means comprises asingle diode 64 having its anode connected to the buss 60, and itscathode connected to the switch 55 which is coupled both to ground andto the voltage source V as in FIG. 2. The operation of the circuit ofFIG. 3 is identical to that of FIG. 2.

It is clear that either mechanical or electronic switching means may beemployed for connecting the anodes of the diodes either to ground or tothe positive voltage source V Tubes, transistors, or any other suitablemeans may be employed to provide electronic switching.

What is claimed is:

l. A counting circuit comprising a multiposition electron beam tubeadapted to operate with crossed electric and magnetic fields including acathode, a plurality of groups of electrodes surrounding said cathode,each of said groups of electrodes including a target output electrodeand a spade electrode adapted to hold an electron beam on itscorresponding target electrode and a switching electrode for switchingan electron beam from one group of electrodes to the next, a source ofswitching signals coupled to each of said switching electrodes, andcircuit means coupled to all of said switching electrodes and adapted tooperate in two states in one of which it applies an operating potentialto said switching electrodes which allows them to perform their normalswitching function in response to signals from said source of switchingsignals and in the other of which it applies a different potential tosaid switching electrodes so that said switching electrodes are disabledand do not perform their normal switching function when switchingsignals are applied thereto from said source of switching signals.

2. A counting circuit comprising a multi-position electron beam tubeadapted to operate with crossed electric and magnetic fields including acathode, a plurality of groups of electrodes surrounding said cathode,each of said groups of electrodes including a target output electrodeand a spade electrode adapted to hold an electron beam on itscorresponding target electrode and a switching electrode for switchingan electron beam from one group of electrodes to the next, a source ofswitching signals coupled to each of said switching electrodes, andunidirectional current fiow means coupled to all of said switchinelectrodes adapted to operate in two states in one of which it applies abias potential to said switching electrodes so that said switchingelectrodes perform their normal switching function in response tosignals from said source of switching signals and in the other of whichit applies a lower bias potential to said switching electrodes so thatsaid switching electrodes are unable to perform their normal switchingfunction in response to switching signals from said source of switchingsignals.

3. A counting circuit comprising a multi-position electron beam tubeadapted to operate with crossed electric and magnetic fields including acathode, a plurality of groups of electrodes surrounding said cathode,each of said groups of electrodes including a target output electrodeand a spade electrode adapted to hold an electron beam on itscorresponding target electrode and a switching electrode for switchingan electron beam from one group of electrodes to the next, driving meanscoupled to said switching electrodes for switching an electron beam fromposition to position in said tube, diode means coupled to all of saidswitching electrodes, and circuit means coupled to said diode means foroperating said diode means in two states in one of which the diode meansapplies a positive bias voltage to said switching electrodes so thatsaid switching electrodes perform their normal switching function inresponse to said driving means and in the other state said diode meansapplies a voltage to said switching electrodes which disables saidswitching electrodes and prevents them from performing their normalswitching function in response to said driving means.

4. A counting circuit comprising a multi-position electron beam tubeadapted to operate with crossed electric and magnetic fields including acathode, a plurality of groups of electrodes surrounding said cathode,each of said groups of electrodes including a target output electrodeand a spade electrode adapted to hold an electron beam on itscorresponding target electrode and a switching electrode for switchingan electron beam from one group of electrodes to the next, saidswitching electrodes being connected in two sets with successive gridsbeing connected in different sets, driving means coupled to said sets ofswitching electrodes for switching an electron beam from position toposition in said tube, and circuit means coupled to all of saidswitching electrodes adapted to operate in two states in one of which itapplies an operating potential to said switching electrodes which allowsthem to perform their normal switching function in response to switchingsignals from said driving means and in the other of which it applies adifferent potential to said switching electrodes so that said switchingelec- 5 trodes are disabled and do not perform their normal switchingfunction when switching signals are applied thereto from said drivingmeans.

5. A counting circuit comprising a multi-position electron beam tubeadapted to operate with crossed electric and magnetic fields including acathode, a plurality of groups of electrodes surrounding said cathode,each of said groups of electrodes including a target output electrodeand a spade electrode adapted to hold an electron beam on itscorresponding target electrode and a switching electrode for switchingan electron beam from one group of electrodes to the next, all of saidswitching electrodes being connected together, a source of switchingsignals coupled to said switching electrodes, and circuit means coupledto all of said switching electrodes adapted 15 2,371,399

to operate in two states in one of which it applies an operatingpotential to said switching electrodes which allows them to performtheir normal switching function in response to signals from said sourceof switching signals and in the other of which it applies a differentpotential to said switching electrodes so that said switching electrodesare disabled and do not perform their normal switching function whenswitching signals are applied thereto from said source of switchingsignals.

References Cited in the file of this patent UNITED STATES PATENTSScuitto Ian. 27, 1959

